Field
Telecommunications systems that employ a relay node can benefit from relay control channel search space configuration. In particular, such systems can benefit from improved search space design and potential reductions in the amount of blind detections for a relay node.
Description of the Related Art
Relay is one approach to extend cell coverage and enhanced cell capacity with a low cost for the Long Term Evolution Advanced (LTE-A) system. There are many kinds of relays relevant to the Third Generation Partnership Project (3GPP) which might be applicable to difference scenarios. In particular, relays can be classified as “type 1” or “type 2.” A type 1 relay is an inband relay, which can use the same frequency band for a backhaul link and an access link. A type 2 relay, in contrast, is an outband relay, which can use a different frequency band for the backhaul link and the access link.
A relay node (RN), sometimes itself called the “relay,” can be in control of cells of its own. These cells can appear to a user equipment (UE) as separate cells from the donor cell. The donor cell can be the cell of the base station, such an evolved node B (eNB), to which the RN is connected. Furthermore, each of the UEs connected to the RN can likewise be referred to as relay nodes. A unique physical-layer cell identity (ID) can be provided in each of the cells of the RN. The RN can transmit its own synchronization channels, reference symbols, and the like. The UE can receive scheduling information and hybrid automatic repeat request (HARQ) feedback directly from the relay node and send its control channels—scheduling request (SR), channel quality indicator (CQI), and acknowledgment (ACK)—to the relay node.
For type 1 relays, in may be useful to define a relay-physical downlink (DL) control channel (R-PDCCH) for the backhaul. However, little has been conventionally done to treat the R-PDCCH search space over the DL backhaul subframe. The R-PDCCH on the DL backhaul subframe may begin, for example, on the fourth orthogonal frequency division multiplexing (OFDM) symbol. Furthermore, cell-specific reference signals (CRS) and demodulation reference signals (DM RS) may be used over the DL backhaul subframe.